Image Quality and Radiation Dose in CT Venography Using Model-Based Iterative Reconstruction at 80 kVp versus Adaptive Statistical Iterative Reconstruction-V at 70 kVp

OBJECTIVE: To compare the objective and subjective image quality indicators and radiation doses of computed tomography (CT) venography performed using model-based iterative reconstruction (MBIR) at 80 kVp and adaptive statistical iterative reconstruction (ASIR)-V at 70 kVp. MATERIALS AND METHODS: Eighty-three patients who had undergone CT venography of the lower extremities with MBIR at 80 kVp (Group A; 21 men and 20 women; mean age, 55.5 years) or ASIR-V at 70 kVp (Group B; 18 men and 24 women; mean age, 57.3 years) were enrolled. Two radiologists retrospectively evaluated the objective (vascular enhancement, image noise, signal-to-noise ratio [SNR], contrast-to-noise ratio [CNR]) and subjective (quantum mottle, delineation of contour, venous enhancement) image quality indicators at the inferior vena cava and femoral and popliteal veins. Clinical information, radiation dose, reconstruction time, and objective and subjective image quality indicators were compared between groups A and B. RESULTS: Vascular enhancement, SNR, and CNR were significantly greater in Group B than in Group A (p ≤ 0.015). Image noise was significantly lower in Group B (p ≤ 0.021), and all subjective image quality indicators, except for delineation of vein contours, were significantly better in Group B (p ≤ 0.021). Mean reconstruction time was significantly shorter in Group B than in Group A (1 min 43 s vs. 131 min 1 s; p < 0.001). Clinical information and radiation dose were not significantly different between the two groups. CONCLUSION: CT venography using ASIR-V at 70 kVp was better than MBIR at 80 kVp in terms of image quality and reconstruction time at similar radiation doses.

Non-invasive MDCT Pulmonary Angiography in Unselected Patients with suspected Pulmonary Thrombo- Embolism.

Background: Pulmonary Thrombo-Embolism (PE) is a common and potentially lethal complication of deep venous Thrombosis (DVT). High sensitivity and specificity of Multi Detector Computed Tomography Pulmonary Angiography (MDCT-PA) in direct visualization of embolic material within the pulmonary arteries is due to its improved spatial and temporal resolution. Methods: We conducted a Prospective study to evaluate Non-invasive 256 Slice MDCT-PA in one hundred unselected patients with clinically suspected Pulmonary Embolism. Results: The total number of patients with thrombo-embolic disease in our study was 35 (35%), out of which acute PE & acute DVT were observed in 32% and 8% respectively. The percentage of Sub-segmental emboli among patients with acute PE was 34.37%, segmental thrombi was 87.5% and central thrombi was 96.87%.Conclusion: MDCT-PA possess the advantage of direct visualization and quantification of thrombo-embolic material and hence we advocate it to be the first-line imaging study for patients with clinically suspected PE.

Análisis del rol de la venografía de extremidades inferiores por tomografía computada en pacientes con sospecha clínica de tromboembolismo pulmonar / Analysis of the role of ct venography of lower limbs in patients with clinically suspected pulmonary embolism

Objetivos. Determinar el rol de la venografía por tomografía computada e identificar variables que determinen el diagnóstico de trombosis venosa profunda de extremidades inferiores en pacientes con sospecha clínica de TEP y sometidos a angiografía de tórax por tomografía computada. Diseño. Cohorte retrospectiva que evaluó 151 pacientes en los que se realizó venografía de extremidades inferiores - angiografía de tórax mediante tomografía computada. Se tabularon factores de riesgo como la edad, sexo, servicio de proveniencia, riesgo para TEP (según score de Wells), ecotomografía Doppler de EEII previa y sus resultados, diagnóstico y lugar anatómico de TEP y diagnóstico y lugar anatómico de TVP según los resultados obtenidos con la venografía. Resultados. Se dispuso de información completa para 151 pacientes. 40 fueron positivo para TEP (26,5%) y 13 venografías resultaron positivas (8.6% del total). Los casos provenían en un 41,7% de Urgencia; 31,1% de UPC; 19,8% hospitalizados (no crítico); y 7,2% de consultas ambulatorias. De las variables estudiadas, ninguna resultó estadísticamente significativa para predecir el hallazgo de trombosis venosa profunda en concomitancia con la angiografía pulmonar mediante TC. En aquellos pacientes con ultrasonido Doppler contemporáneo, la venografía por tomografía computada no aportó nueva información de aquella ya disponible. Conclusiones. En este estudio no se encontraron variables que a priori apoyen la realización de una fase venográfica en concomitancia con una angiografía de tórax mediante tomografía computada cuando existe la sospecha clínica de tromboe-mbolismo pulmonar. No se justificaría realizar venografía por TC en pacientes con hemodinamia estable y sospecha de TEP.

Objectives. To determine the role of CT venography and identify variables that determine the diagnosis of deep venous thrombosis (DVT) of lower extremities in patients with clinical suspicion of PE, and who underwent chest CT angiography. Design. Retrospective group study that evaluated hundred fifty-one patients in whom lower extremity venography- chest CT angiography was performed. Risk factors were tabulated - such as age, sex, department origin, risk of PE (according to Wells Criteria), previous Doppler ultraso-nography of lower extremities and their results, diagnosis and anatomical site of PE, and diagnosis and anatomical site of DVT according to the results obtained with the venography. Results. Complete data was available for 151 patients. 40 were positive for PE (26.5 percent) and 13 venographs were positive (8.6percent of the total). The case origins were 41.7 percent from Emergency Department, 31.1 percent from ICU, 19.8 percent hospitalized (non-critical) and 7.2 percent from outpatient consultations. Of the variables studied, none resulted statistically significant for predicting the discovery of deep vein thrombosis in conjunction with CT pulmonary angio-graphy. In those patients with contemporary Doppler ultrasound, the CT venography did not provide new information from that already available. Conclusions. In this study we did not find variables that support a priori the realization of a venography phase in conjunction with chest CT angiogram when there is clinical suspicion of pulmonary embolism. Performing CT venography in patients with stable hemodynamics and suspected PE, would not be justified.

Preoperative Assessment of Small Saphenous-Type Varicose Veins by Three-Dimensional CT Venography with Dual-Route Injection / 日本心臓血管外科学会雑誌

The saphenopopliteal junction (SPJ) is found at various levels and has various patterns compared with the saphenofemoral junction. Although this can cause difficulty in the surgical treatment of varicose veins and affect the outcome, there have been few reports on preoperative assessment of the small saphenous vein (SSV) regarding this point. This study was undertaken to evaluate three-dimensional CT venography with dual-route injection for the preoperative assessment of a small saphenous-type varicose vein. We examined a total of 15 legs in 15 patients with a small saphenous-type varicose vein, which were preoperatively evaluated by CT venography and then surgically treated. The patients included 4 men and 11 women with ages ranging from 50 to 80 years old (mean age, 66 years). The grading of varicose veins according to the CEAP classification was C2, C3, C4, and C5 in 3, 4, 6 and 2 legs, respectively. The CT imaging was performed with contrast medium diluted ten-fold, which was injected into the great and small saphenous veins simultaneously. CT venography clearly visualized the lower extremity veins. Whereas the popliteal vein coursed deep above the level of the femoral intercondylar groove, it followed a shallow course below the level of the knee joint. In 11 legs (74%), the SPJ was located in the shallow portion, whereas it was in the deep portion in 4 legs (26%). Among the former group, the SSV was connected to the great saphenous vein via the Giacomini vein in 2 cases, and the gastrocnemius vein was connected to the SSV before the SPJ in 3 cases. Among the latter group, a localized large venous aneurysm with thrombus before its termination was found in one case. In another case, the SSV showed branched termination in the deep portion. Our three-dimensional CT venography with dual-route injection provides more accurate information on venous anatomy in the lower extremity. The accuracy of images acquired by CT venography with dual-route injection was verified by intraoperative findings. Although Doppler ultrasound is essential for examining the presence of regurgitation in the veins and locating the course of a varicose vein in the surgical field, all 15 cases had scheduled surgery under local anesthesia based on accurate preoperative diagnosis. This study suggests that CT venography with dual-route injection is beneficial in preventing undesired complications during surgery and avoiding additional procedures for recurrent varicose veins.

CT Venography for Deep Vein Thrombosis Using a Low Tube Voltage (100 kVp) Setting Could Increase Venous Enhancement and Reduce the Amount of Administered Iodine

OBJECTIVE: To investigate the validity of the 100 kVp setting in CT venography (CTV) in the diagnosis of deep vein thrombosis (DVT), and to evaluate the feasibility of reducing the amount of administered iodine in this setting. MATERIALS AND METHODS: After receiving the contrast medium (CM) of 2.0 mL/kg, 88 patients underwent CTV of the pelvis and lower extremities by using one of four protocols: Group A, 120 kVp setting and 370 mgI/mL CM; group B, 120 kVp and 300 mgI/mL; group C, 100 kVp and 370 mgI/mL; group D, 100 kVp and 300 mgI/mL. The groups were evaluated for venous attenuation, vein-to-muscle contrast-to-noise ratio (CNRVEIN), DVT-to-vein contrast-to-noise ratio (CNRDVT), and subjective degree of venous enhancement and image quality. RESULTS: Venous attenuation and CNRVEIN were significantly higher in group C (144.3 Hounsfield unit [HU] and 11.9), but there was no significant difference between group A (118.0 HU and 8.2) and D (122.4 HU and 7.9). The attenuation value of DVT was not significantly different among the four groups, and group C had a higher absolute CNRDVT than the other groups. The overall diagnostic image quality and venous enhancement were significantly higher in group C, but there was no difference between groups A and D. CONCLUSION: The 100 kVp setting in CTV substantially help improve venous enhancement and CNRVEIN. Furthermore, it enables to reduce the amount of administered iodine while maintaining venous attenuation, as compared with the 120 kVp setting.

MDCT Application in the Vascular System

Helical CT has improved with faster gantry rotation, more powerful X-ray tubes, and improved interpolation algorithms; however, the greatest advance has been made by the recent introduction of multi detector-row computed tomography (MDCT) scanners. Fundamental advantages of MDCT include substantially shorter acquisition times, retrospective creation of thinner or thicker sections from the same raw data, and improved threedimensional (3-D) rendering with diminished helical artifacts. While these features will likely be important to many applications of CT scanning, the greatest impact has been on CT angiography. The advantages of MDCT over single detector-row CT scanners when imaging the vascular system can be broken down into three fundamental improvements, that is, speed (faster scan time), distance (longer coverage), and section thickness (better resolution). This article will focus on how the MDCT technology has substantially improved imaging of the vascular system, including pulmonary artery, aorta and extremity vessels.

Value of CT venography in diagnosis of cerebral venous sinus thrombosis / 临床神经病学杂志

Objective To explore the value of CT venography (CTV) in diagnosis of cerebral venous sinus thrombosis (CVST) . Methods 16 patients with CVST were examined by CTV. 2D and 3D vascular images were reconstructed through workstation. Results Filling-defect was seen as "empty triangle sign" on the axial image.Multiple CVST were displayed in 11 patients,among them,8 cases involved superior sagittal sinus,3 cases involved lateral sinus. Single CVST was displayed in 5 patients,2 cases involved superior sagittal simes,2 cases involved straight sinus,1 case involved inferior sagittal sinus. The irregular narrowing or occlusion of the sinus and dilation of the branch of vein were observed in all 16 patients on 2D or 3D images. Hydrocephalus, cerebral infarction and cerebral hemorrhage were seen in 11 cases, 6 cases and 4 cases respectively. Conclusion CTV is a sensitive and distinctive technique in diagnosing CVST.